CA3196982A1 - Blade for a fan, and a fan using such a blade - Google Patents

Abstract

The present invention disclose a blade (1) for use in a fan (2) as well as a fan (2) with such a blade (1), where said blade (1) has a profile which profile when travelling through air will impart motion to the air, and where said blade (1) has a front side surface (10) and a back side surface (12), said front side surface (10) and back side surface (12) arranged between a leading edge (14) and a trailing edge (16), where the leading edge (14) and the trailing edge (16) are arranged along a longitudinal axis (18), such that the blade (1) in a cross-section orthogonal to the longitudinal axis (18) has a cross-section and that integral inside said cross-section at least for a distance in the blade (1) along the longitudinal axis (18), is provided one or more UV light sources (20), where said UV light sources (20) are arranged to emit light away from said back side surface (12).

Description

PCT/DI(2021/050319 BLADE FOR A FAN, AND A FAN USING SUCH A BLADE
Field of the Invention The present invention is directed to a blade for use in a high volume low speed fan as well as such a fan incorporating such a blade.
Background of the Invention Within the present invention a fan shall be understood as a device, which is suitable to move air by rotating a plurality of blades around a hub/rotor such that the blades will cut the air more or less like an airplane propeller and in this manner induce a velocity to a mass of air. Consequently, the term blade shall be understood as the object/member, which projects from the rotor and travels through the air in order for the profile and the orientation of the blade, as it travels through an air mass, to introduce a velocity to the surrounding air.
Fans are very widely known for example as table fans, where the fans are placed on a table and due to the rotation of the blades, an air current is created for example in order to cool or to ventilate. Likewise, it is well-known to use fans in ceilings in order to create a draft in a room, whereby hot air collected under the ceiling will be circulated downwards into the habitable zone. Likewise, in areas where air condition is widely used, it is desirable to create air circulation in order for the cool air to be circulated around the entire habitable zone. Not in all circumstances will the air condition unit be able to distribute the cooled air and as such fans are used in order to create extra venti-lation.
In the field of fans one particular type of fan is the so-called high-volume low speed fans (HVLS), which are characterized by having a very large blade area and on the other hand rotate at a very slow speed. In this manner relatively large volumes of air are being moved without creating a draft, due to the relatively low speed which thereby impart motion to the ambient air. A draft is very undesirable, particularly for persons working in the habitable zone. It is this type of fan, i.e. HVLS fan the present invention is directed to.

2 It is a general problem with large indoor areas/arenas, where a number of persons are working or otherwise spend time together to provide an environment with fresh and clean air without creating drafts or the spread of, for example contagious diseases.
To this end it has been known to provide various disinfectant solutions such as special air cleaners or air treatment devices, where the air to be introduced into the environment has been disinfected prior to being introduced into the environment. The disinfection step may for example be the exposure of the air to heating and cooling UV-C
light or other measures.
CN211778100U disclose an ordinary ceiling fan which has been provided with an ul-traviolet light source on an upper surface of the blade. Traditionally blades of ordinary fans travel with relatively high velocities, and as such the blades of the fan, need not be aerodynamically optimised. In the CN211778100U the ultraviolet light source is mounted on top of the blade. This causes turbulence which again causes the blades not to impact so much air as if the air had not been disturbed. Furthermore, turbulence also creates noise.
Object of the Invention It is the object of the present invention to provide a system, where already used devices for creating a suitable indoor climate are further enhanced by providing additional ger-mi ci dally effective features.
Description of the Invention The invention addresses this by providing a high volume low velocity fan, where said blade has a profile, which profile when travelling through air will impart motion to the air, and where said blade has a front side surface and a back side surface, said front side surface and back side surface arranged between a leading edge and a trailing edge, where the leading edge and the trailing edge are arranged along a longitudinal axis, such that the blade in a cross-section orthogonal to the longitudinal axis has a cross-section and that integral inside said cross-section at least for a distance in the blade along the longitudinal axis, is provided one or more UV light sources, where said UV
light sources are arranged to emit light away from said back side surface.

3 A general problem with UV-C light is that it should not be directed directly at persons in that it might impair vision and create problems with the skins, as it has been known to be able to cause skin cancer and the like. Therefore, by providing the UV
light source such that it emits light away from the back side of surface and this is also the same as saying that it emits light away from the habitable 70ne, it is avoided that UV
light is emitted directly into the habitable zone. Furthermore, by integrating the light source inside the cross-section of blade the air dynamic characteristics of the blade are not altered and as such the blade may remain as effective as it was originally designed to irrespective of the fact that one or more light sources are integrated in the blade. Partic-ularly for HVLS fans it is important to maintain the aerodynamic properties, such that even though the blades travel through the air at a slow speed each blade will be able to effectively impart motion to the air. Therefore it is important that the blades only moves the air ¨ preferably in a downward direction, and disturbs the air as little as possible (i.e.
does not create turbulence) during the blades motion through the air.
At least within the present invention the formulation "impart motion to the air" shall be understood as the blades during the sweeping motion through the air forces the air in a direction such that the air attains a velocity. The blade may achieve this for example by being angled with respect to the direction in which it is moving through the air, or by being provided with an aerodynamic profile which profile will cause the air to move. It should also be understood that the air direction/movement may be either away from the back side of the blade or towards the back side. There will, due to the rotation of the blade mounted in a fan also be a substantial cross-flow almost along the blade. However for the intent of the invention the air direction is not so important as long as air is moved into the zone where the UV light source emits light.
In a further advantageous embodiment of the invention the one or more UV light sources are arranged in a reflector, and where a transparent or translucent cover is positioned covering the UV light sources, such that said transparent or translucent cover is integral and/or flush with said back side.
It is clear that the provision of a reflector will concentrate the emitted light in a specified zone, such that the light emitted from the back side of the blade will be concentrated in the zone defined by the shape of the reflector. By furthermore covering the light sources with a transparent or translucent cover, the integration of light sources into the blade

4 will, as already discussed above, not have any influences on the blades' aerodynamic characteristics. The cover may typically be made from quartz glass but also other types of transparent or translucent cover may be used, for example plexiglass or other mate-rials, as long as they substantially allow the light to be emitted through the cover mate-ri al In a further advantageous embodiment of the invention the one or more UV light sources extends 10 % to 100% of the length of the blade in the direction of the longitudinal axis.
In order to have a germicidal effective effect the light source needs to emit light with a certain energy level in order to be able to destroy bacteria, virus and other pathogens.
The destructive characteristic of UV-C light is created by deactivating DNA of the bac-teria, virus or pathogens. The UV-C light does not destroy the DNA but does destroy the ability of the DNA to replicate by causing damage to the nucleic acid of microor-gani sms by forming covalent bonds between certain adjacent bases in the DNA
struc-ture. The formation of such bonds prevents the DNA from being unzipped for replica-tions and consequently the organism is unable to reproduce. Furthermore, should the organism try to replicate it will die due to the destruction of the DNA.
However, in order to be effective, the bacteria, virus or the pathogens has to be exposed to a certain dose of ultraviolet light. For a blade being fastened to a rotor travelling through an airmass, the concentration or doses delivered to a virus, bacteria or other pathogen in that airmass obviously depends on the amount of watts emitted from the light source, the time the light source is present i.e. is radiating that particular virus, bacteria or other pathogen and furthermore the virus, bacteria or other pathogen distance to the light source. All these factors influence the success of the treatment and thereby how effective the UV-C light arranged on the back side of the blade is in disinfecting the air through which it travels.
Therefore, in some embodiments the extent of the blade and thereby the extent of the light source along the longitudinal axis of the blade allows for large areas to be treated as the blade travels through the air.
In another advantageous embodiment the one or more light sources extends 20 %
to 100% of the width between said leading edge and trailing edge.

5 In a further advantageous embodiment, the one or more UV light sources are UV-C
light sources having wave lengths in the interval from 100 nanometers to 300 nanome-ters. Compared to the entire spectrum of unseen light and visible light 100-300 nanome-5 ters i s a very narrow band However, exposing ambient air to UV-C light in such a broad spectrum does, in addition to the germicidally effective part of the spectrum, also intro-duce some disadvantages. When oxygen is exposed to UV-C light below approximately 250 nanometers the oxygen will be converted into ozone, which is detrimental to an indoor climate/environment. For this purpose, the ultraviolet spectrum, which the pre-sent invention emits, is in a further advantageous embodiment advantageously limited to UV-C wavelength from 253 nanometers to 300 nanometers. Particularly close to 253 and 254 nanometers the wave lengths are particularly destructive for the bacteria, vira and pathogens, as described above.
One of the other factors having an influence on the effectiveness of the blade is the intensity of the emitted light. Typically, intensity is measured as irradiance in W/cm2.
However safe exposures for human beings is measured in pW/cm2.With the present invention where it is avoided that the UV lights emits light directly into the habitable zone, it is possible to use relatively strong UV lights without surpassing the threshold for damaging UV exposure. For this reason the irradiance from the UV-C light sources is limited to below 100 W/cm2. The high Wattage is used when LED lights are used as UV light source whereas for traditional low and high pressure UV lights the wattage may be in a much lower range of approx. 0,1 W/cm2.
In a further advantageous embodiment two or more light sources are arranged in paral-lel, and where a control unit provided either in or outside the blade controls the light sources such that one, two or more light sources may be active at a desired time. With this embodiment it is possible to adjust the emitted light both with respect to area and intensity such that for example in periods where no personnel are present in the room, in which it is desirable to disinfect the air, the intensity may be increased in order to thoroughly disinfect the air in the room, whereas in periods where the room is filled with personnel it might be disadvantageous to have the lights at high intensity and the fan at high speed. In these instances it is possible to increase the area but lower the

6 intensity and still maintain an effective germicidal effect by using the UV-C
light sources in the blades.
In a particularly advantageous embodiment the blade is used in a high-volume low speed ceiling fan, where the blade will typically have a length along the longitudinal axis between 50 cm and 350 cm and/or the width orthogonal to the longitudinal axis is between 5 cm and 40 cm, and/or the thickness of the blade at the blades thickest point in a direction orthogonal to a plane defined by the longitudinal axis and the width di-rection is between 1 cm and 12 cm.
High-volume low speed fans are typically used in environments, where it is desirable to move large volumes of air at low velocities such that draft (the feeling of a wind blowing) is completely avoided but still the air is circulated in order to keep a fresh and a healthy indoor environment.
In a further advantageous embodiment, the UV light sources may be in the shape of a thin film applied to back surface of the plate, particularly in cases where the light sources are LEDs, this is a very advantageous embodiment.
LEDs tend to have a lower intensity than traditional low pressure or medium pressure UV lamps, and as such requires more space in order to be able to create germicidally effective doses.
Within this description thin film shall be understood as a very thin layer, only fractions of millimeters up to 2-3 mm thickness of a material in which LED light sources are embedded, or a thin film integrating the diodes. Such a film may be adhered to the surface or printed directly onto the surface of the blade.
In a further advantageous embodiment an aperture shield is provided covering the UVC
light source, where said aperture shield is integral with the back side surface of the blade, and where the aperture shield is provided with one or more apertures, allowing the light to emit from the back side surface of the blade.
Many standard UVC light sources emit too concentrated a dose of UVC ¨ see discussion above about health and environment concerns. By positioning a aperture shield having one or more apertures in front of the light source, a physical limitation on the emitted

7 light is in place. Moreover, the one or more apertures may be designed/sized such that the desired dose of UVC light is allowed to be emitted. It is therefore possible to use the same type of light source for all applications. As the electronic circuitry, light source socket etc has to be adapted to the particular light source, it provides an important ad-vantage to be able to alter/control the emitted light by a simple mechanical aperture shield.
The invention is also directed to a fan, in particular a high-volume low speed fan pro-vided with at least one blade according to any of claims 1 to 9, where said at least one blade is arranged in a rotor, such that a motor may rotate the rotor and thereby the blade with a determined speed through the ambient air, whereby the back side of the blade passes a specified area per time unit and wherein a control unit is provided wherein said control unit comprises predetermined data correlating the blades speed through the air with the emitted light intensity, such that the air passing the back side of the blade is exposing the air to a germicidally effective light dose.
As already discussed above, it is necessary to assure that a certain dose of UV-C light is emitted in order for the light to be germicidally effective. However, with the present invention it is not necessary to kill 100% of any bacteria, virus or pathogens with each sweep, since the air is brought to move due to the action of the blades. The air will be circulating and as such the bacteria, virus or pathogens may due to the turbulence cre-ated by the fan pass the light zone, i.e. the zone where the lights are emitting light above the back surface, a number of times and as such over the course of some time each virus, bacteria or pathogen will be exposed to relatively high doses and as such an effective killing procedure will be achieved. In order to assure this, the fan is provided with a control unit, which has been preprogrammed, such that at the certain speed of the blades through the air, a certain light intensity will be emitted in order to assure that a germi-cidally effective light dose is emitted or transferred to the ambient air adjacent the back side of the blades. Again, this germicidally effective light dose may not be 100% effec-tivefor each sweep of the blade through the air, as already mentioned above.
In a further advantageous embodiment, the fan has between 3 and 8 blades, where each blade is provided with features as disclosed in any of the claims 1-10. It is clear that by providing a fan, where 1, 2 or 3 blades for example are provided with light sources and

8 additional blades are not provided with light sources, the ability of the fan to emit a germicidally effective light dose is somewhat reduced. Therefore, by providing all the blades with light sources, a very effective zone is created above the blades, where the light dose continuously is germicidally effective. Furthermore, by being able to rotate the fan blades about an axis orthogonal to the longitudinal axis of the blades, and thereby circulate the air, the air will pass into the light zone many times and as such there will be ample opportunity to expose all bacteria and virus, or other pathogen to germicidally effective doses. In this manner, a very effective disinfection is achieved.
Description of the Drawing The invention will now be explained with the reference to the accompanying drawing, wherein:
figure 1 illustrates a blade according to the invention;
figure 2 illustrates a cross section indicated by AA(see figure 1) perpendicular to the longitudinal axis;
figure 3 illustrates a blade incorporated into a fan;
figure 4 illustrates a zone 38 in which the UV light sources due to the rotation around the vertical axis will expose the ambient air above the back side of the blades to UV
light;
figure 5 illustrates a curve for a LED UV light source where the wavelength of UV-C
light is on the X-axis and the intensity is on the Y-axis;
figure 6 illustrates a curve for a traditional low and medium pressure UV
light source where the wavelength of UV-C light is on the X-axis and the intensity is on the Y-axis.
Figure 7 illustrates various apertures shields suitable to be integrated in a blade.
Figure 8 illustrates a mounting bracket.
Detailed Description of the Invention In figure 1 is illustrated a blade 1 according to the invention. The blade 1 will, when travelling through the air impart motion to air due to the air dynamic profile, as will be discussed with reference to figure 2. The blade has a front side surface 10 and a back side surface 12. The surfaces 10, 12 are arranged between a leading edge 14 and a trail-ing edge 16. The leading edge and the trailing edge 14, 16 are arranged along a longi-tudinal axis indicated by the dash line 18.

9 The blade 1 is on the back side 12 provided with one or more UV light sources 20.
In this embodiment the trailing and leading edges 14, 16 are parallel and the UV light sources are arranged also parallel to the longitudinal axis 18. It is, however, foreseen that particularly the leading and trailing edges 14, 16 may have other orientations along the longitudinal axis depending on the air dynamic characteristics, which it is a possible or desirable to provide for the blade as such.
In figure 2 a cross section indicated by AA perpendicular to the longitudinal axis 18 (see figure 1) is illustrated. The blade 1 has an air dynamic cross section such that be-tween the leading edge and trailing edge the back side 12 and the front side surface 10 are provided with curved profiles such that as the blade 1 travels through the air with the leading edge 14 first, the air will be forced into motion, in this example with the cross section illustrated in figure 2, the air below the blade 1 will be forced downwards.
Adjacent the leading edge 14 is provided a reflector 22 and two UV-C light sources 20, 20'. As the light sources 20, 20' are activated, the light sources 20, 20' will with the help of the reflector 22 emit light emitting from the back side 12 away from the blade 1 as such.
The blade, as discussed above with reference to figures 1 and 2 is particularly suitable for incorporation into a fan 2, as illustrated in figure 3. A number of blades 1 are fas-tened to a rotor 30, where the rotor comprises a motor hub 32 and fastening means for example to a ceiling. In this manner the rotor 30 with the attached blades 1 may rotate the blades around the vertical axis 34. As the blades are provided with a cross section, as discussed in figure 2, the rotation of the blades 1 around the vertical axis 34 will create a downforce i.e. the air will be forced downwards. Due to the blades forcing the air downwards, air will also move upwards in a big rotational movement, as indicated by the arrow 36. In this manner, air in a room, where a fan 2, as illustrated in figure 3, is installed, will be exposed to a slow circle of movement such that air on one side of the fan is forced downwards, whereas new air will be forced into the vicinity of the fan 2, and as such be exposed to the sweeping action of the blades 1 forcing the air down-wards.

PCT/D1(2021/050319 This sweeping action particularly with respect to blades 1 wherein UV light sources 20 are arranged, as mentioned above, will, as indicated in figure 4, create a zone 38 in which the UV light sources due to the rotation around the vertical axis 34 will expose the ambient air above the back side 12 of the blades to UV light. In the embodiment 5 explained with reference to figure 3 only one blade is indicated as being provided with UV light sources 20 but naturally one, two or any numbers of blades may be provided with UV light sources. In this manner, it is possible to regulate the intensity of the light in the zone 38, such that a germicidally effective dose of UV-C light, particularly UV-C light with a wavelength of approximately 254 nanometres (specifically 253,7 is de-

10 sirable) is created.
In figure 5 a curve for a LED light source is illustrated, where the wavelength of UV-C
light is on the X-axis and the intensity is on the Y-axis. As indicated by the dashed lines the germicidal effectiveness of the light has an apex broadly between 256 and 268 na-1 5 nom etres, where a particular light source (not necessarily the light source used for the present invention) has an apex in the area of 266 nm. As explained above, the UV-C
light may have diametral effects, for example that it converts oxygen to ozone and for these reasons, it is desirable to select a wavelength, which is germicidally effective and at the same does not have any side effects. Therefore, with the present invention wave-lengths around 254 nanometres are selected.
Similarly to fig. 5 a curve for traditional low and medium pressure UV lamps is indi-cated in fig 6.
The type of UV-C light source may be decided according to how much space is availa-ble in the profile of the blade, see for example figure 2, the price of the UV-C light sources and also the desired intensity being emitted in order to create a germicidally effective dose in the vicinity of the back side 12 of the blade. For this reason, traditional low- or high-pressure UV lamps may be used but also LEDs may be used. If LEDs are used they may advantageously be attached to the back side 12 of the blade 1 as a thin film covering substantially the entire back side surface in order to be able to provide sufficient doses of the UV-C light but also providing a wide spectre of intensity due to the possibility of igniting sections of the LEDs or all of the LEDs according to pre-programmed parameters.

11 In order to be able to provide different reductions in light intensity, different aperture shields may be used as illustrated with reference to figure 7. In this embodiment the aperture shields all have a standard size and may therefore be interchanged in the same recess/cavity provided in a blade as discussed above The aperture shield 40 has a very narrow slit 42 corresponding to a 95%
reduction com-pared to a situation where no aperture shield is provided in front of the UVC
light source. Likewise, the aperture shield 44 has a slightly wider slit 46 which provides a 900/0 reduction. The further aperture shield 48 having two parallel slits 50,50' provides a 800/0 reduction and the further two examples 52, 54 provides 60 %, 40 %
respectively.
Naturally, the design of the aperture shields may be different and the slits may be re-placed by apertures or any other geometrical design as it is the size of the opening which is important with respect to the present invention in order to reduce the emitted light and adjust the light emission from the light source to a desired level in the ambient environment.
Furthermore as illustrated in fig. 8 a bracket construction 60 is provided for mounting the fan to a surface 62, for example a ceiling or as in this example the underside of a beam.
As ceilings may be provided at an angle relative to horizontal, it is necessary that the bracket 60 is able to orient a shaft 64 substantially vertically (as indicated by dashed line 66) in order for the blades of the fan (see fig. 3 or 4) to move through the air in a horizontal plane. The fan including motor, blades etc are attached to the shaft 64.
The upper end 68 of the shaft 64 has a bulbous part (part of a ball). The diameter of this ball is larger than an aperture provided in a lower flange 70 of the bracket 60. In this manner the shaft 64 may be inserted through the aperture, but the bulbous part will not pass. Due to the design of the bulbous part/ball shape the orientation of the shaft 64 relative to vertical 66 and the lower flange 70 may easily be adjusted, such that the shaft is substantially vertical whereas the rest of the bracket may have any (random) orienta-tion dictated by the surface 62 onto which it is mounted.

PCT/D1(2021/050319

12 A fixation plate 72 is provided above the lower flange 70. This fixation plate is provided with a second aperture, such that the fixation plate 72 may be placed over the bulbous part and the bulbous part extend slightly, in use above the fixation plate 72.
By urging the fixation plate 72 towards the lower flange 70, when fitted around the bulbous part 68, the fixation plate 72 in combination with the lower flange 70 will fixate the bulbous part 68 when the fixation plate 72 is urged towards the lower flange 70.
Thereby, the orientation of the shaft 64 is fixated in the desired orientation relative to the bracket 60.
In order to urge the fixation plate 72 towards the lower flange 70, bolts 74 may be arranged at desired positions around the periphery of the bulbous part 68, such that when tightening the bolts 74 the fixation plate 72 and the lower flange 70 will be urged to-wards each other, thereby squeezing/fixating the bulbous part 68.

Claims (14)

13

1. Blade for use in a fan, where said blade has a profile which profile when travelling through air will impart motion to the air, and where said blade has a front side surface and a back side surface, said front side surface and back side surface ar-ranged between a leading edge and a trailing edge, where the leading edge and the trailing edge are arranged along a longitudinal axis, such that the blade in a cross-section orthogonal to the longitudinal axis has a cross-section and that integral in-side said cross-section at least for a distance in the blade along the longitudinal axis, is provided one or more UV light sources, where said UV light sources are arranged to emit light away from said back side surface.

2. Blade according to claim 1 wherein the one or more UV light sources are arranged in a reflector, and where a transparent or translucent cover is positioned covering the UV light sources, such that said transparent or translucent cover is integral and/or flush with said back side.

3. Blade according to claim 1 or 2 where the one or more UV light sources extends % to 100% of the length of the blade in the direction of the longitudinal axis.

4. Blade according to claim 1, 2 or 3 where the one or rnore UV light sources extends % to 100% of the width between said leading edge and trailing edge.

5. Blade according to any preceding claim wherein the one or more UV light sources are UV-C light sources, have wave lengths in the interval from 100 nanometers to 300 nanometers.

6. Blade according to claim 5 wherein the UV-C wavelength is from 253 nanometers to 300 nanometers.

7. Blade according to any preceding claim wherein the irradiance from the UV-C light sources is limited to below 100 W/crn2.

8. Blade according to any preceding claim wherein two or more light sources are ar-ranged in parallel, and where a control unit provided either in or outside the blade controls the light sources such that one, two or more light sources may be active at a desired time.

9. Blade according to any preceding claim wherein the length of the blade along the longitudinal axi s is between 50 cm and 350 cm and/or the width orthogonal to the longitudinal axis is between 5 cm and 40 cm, and/or the thickness of the blade at the blades thickest point in a direction orthogonal to a plane defined by the longi-tudinal axis and the width direction is between 1 cm and 12 cm.

10. Blade according to any of claims 1 to 7, wherein the UV light source is a thin film applied to the back surface of the blade, where optionally the light sources are LED.

11. Blade according to any preceding claim wherein a aperture shield is provided cov-ering the UVc light source, where said aperture shield is integral with the back side surface of the blade, and where the aperture shield is provided with one or more apertures, allowing the light to emit from the back side surface of the blade.

12. A high-volume low speed fan, provided with at least one blade according to any of claims 1 to 10, where said at least one blade is arranged in a rotor, such that a motor may rotate the rotor and thereby the blade with a determined speed through the ambient air, whereby the back side of the blade passes a specified area per time unit and wherein a control unit is provided vvherein said control unit comprises prede-termined data correlating the blades speed through the air with the emitted light intensity, such that the air passing the back side of the blade is exposing the air to a germicidally effective light dose.

13. The high-volume low speed fan according to claim 11 wherein the between three and five/8 blades are provided where each blade is provided with features as dis-closed in any of claims 1 to 8.

14. The high volume I ovv speed fan according to claim 12, wherein a shaft extends, from the fan, and where said shaft in a free distal end is provided with a ball, and where a mounting bracket suitable to mount the fan to a surface is provided, said bracket comprises a first plate member provided with an aperture larger than the diameter of the shaft, but smaller than the diameter of the ball, as well as flanges suitable to be mounted to said surface, and a second plate member provided with an aperture smaller than the diameter of the ball and with apertures, and where the ball is positioned between the two plates such that the first plate and the second plate engages the ball and where said plates may be urged together fixating the ball and thereby also the shaft.